Skin lesions such as lipomas and hairy patches found over the spine are well recognised as markers of rare, concealed underlying spinal abnormalities—otherwise known as occult spinal dysraphism (OSD) (table 1). Detection of OSD in infants is difficult because an abnormal neurological examination is often not apparent until the child becomes ambulatory, or even later. The associated spinal abnormalities include intraspinal lipomas, cord tethering and split cord malformation or diastematomyelia. Skin and neural tissues have common ectodermal origins, therefore anomalies of both may occur simultaneously. The discovery of a midline skin lesion in an otherwise well, asymptomatic neonate or child often prompts a search for OSD using imaging. However, it is sometimes not clear which lesions warrant imaging—particularly in the case of skin dimples, and so-called birth marks or cutaneous vascular lesions that are all common in infants. The purpose of this article is to clarify the indications for imaging, describe the advantages and disadvantages of the two main imaging modalities, and demonstrate some of the imaging findings that may be reported in these patients.

WHY LOOK FOR OSD?

Infants and children with OSD may develop symptoms as they grow due to distortion of the spinal cord and nerve roots. This results in neurological sequelae in the lower limbs, urinary and bowel symptoms. In the tethered cord syndrome (TCS) cord traction occurring as a result of growth is thought to impair the microcirculation of the cord leading to progressive cord ischaemia.¹ Surgical intervention for spinal lesions such as cord tethering or split cord malformation before the onset of symptoms may prevent irreversible neurological damage.^2,3 However, some clinicians advocate lifelong surveillance with surgical intervention only after the onset of symptoms.³ Patients with anorectal and urogenital malformations including VATER (vertebral anomalies, anorectal malformations, tracheo-(o)esophageal …